Mobile devices such as wireless telephones and PDAs, for example, allow subscribers of a wireless service provider to wirelessly transmit and receive telephone calls, email messages, text messages, and various types of content over wireless networks. Most mobile devices in use today provide users with the ability to input and store various types of data, such as, for example, telephone numbers, names, addresses, schedules, photographs, etc. Such mobile devices generally include some type of computer processing device that functions as a central processing unit (CPU) and some type of memory device for storing various types of data, network settings, personal passwords, content (e.g., photographs), and other types of information. In addition, some mobile devices implement near-field communication technology, which allows a subscriber's credit card information to be stored in the mobile device so that the mobile device is able to make contactless payments with a point-of-purchase (POP) terminal.
When a mobile device is lost or stolen, a person who finds or who has stolen the mobile device may be attempt to use the mobile device and/or to access information stored in the memory device of the mobile device. To prevent unauthorized users from being able to access information stored in the memory device, some mobile devices provide the subscriber with the ability to configure the mobile device with a password that prevents an unauthorized user from accessing information stored in the memory device and/or from using the mobile device to access the wireless network. However, various techniques can be used to hack into a mobile device even if the subscriber has password protected the mobile device. Therefore, password protecting a mobile device is not totally effective at preventing unauthorized users from using the mobile device and/or from accessing information stored in the memory device of the mobile device.
A subscriber identity module (SIM) card is a component of a mobile device that is configured to operate wirelessly over a Global System for Mobile Communications (GSM) network. GSM is an international wireless standard that is used around the world. Each SIM card has a unique number stored in it, known as the International Mobile Subscriber Identity (IMSI) number, which identifies the subscriber's account information to the GSM network and allows the network to determine a rate plan and billing information to be used. SIM cards are completely interchangeable between Mobile devices configured to operate over GSM networks to provide greater flexibility of devices on GSM networks than CDMA allows on its networks. The SIM card is typically contained in a slot behind the direct current (dc) power supply of the mobile device. The SIM card can be easily removed by first removing the battery supply and then removing the SIM card from the slot. After the SIM card has been removed, it can be reinserted into the slot or replaced with a different SIM card that is inserted into the slot.
The IMSI number is transmitted wirelessly along with other information from the mobile device to the wireless network when the user attempts to setup a session (e.g., place a telephone call, transmit an email message, transmit a text message, etc.). The IMSI number is typically also periodically transmitted by the mobile device to the network to enable the network to ascertain the geographical location of the mobile device in real-time. Equipment within the network receives the IMSI number and compares it with a list of authorized IMSI numbers associated with authorized subscribers to determine whether or not the IMSI number corresponds to an authorized subscriber, i.e., a subscriber who is authorized to access the network. If the network equipment determines that the received IMSI number does not correspond to an authorized subscriber, the network will not allow the mobile device to communicate over the network.
Typically, when a subscriber realizes that his or her mobile device has been lost or stolen, the subscriber will contact the wireless service provider and inform the provider that the mobile device has been lost or stolen. The service provider typically will then “tag” the mobile device as being lost or stolen and remove the IMSI number from the list of authorized IMSI numbers. Subsequently, if an unauthorized user attempts to setup a call session using the lost or stolen mobile device, the network will determine that the mobile device is no longer authorized and therefore will not allow the call session to occur. However, if the unauthorized user replaces the SIM card that is in the mobile device with a different SIM card that is authorized on the network, such as a pre-paid SIM card, the unauthorized user will often be able to access the network.
While the aforementioned techniques provide some protection against unauthorized persons using a lost or stolen mobile device and/or accessing information stored in the mobile device, those techniques do not guarantee that an unauthorized person will be prevented from using and/or accessing information stored in a lost or stolen mobile device. Accordingly, a need exists for a way to guarantee that an unauthorized user of a lost or stolen mobile device will be prevented from using the mobile device over a wireless network and from accessing information stored in the mobile device.